The present invention relates to a synthetic resin grommet used, for example, when parts for an automobile or parts for a home electric appliance (hereinafter simply referred to as parts) are attached to a body of the car or of the appliance (hereinafter simply referred to as body), respectively.
A synthetic resin grommet as shown in FIG. 4 is widely used for attaching parts to the body 26 using bolts. The grommet has a cylindrical body 21, a flange portion 22 arranged at a predetermined position of the cylindrical body 21 and stopping claws 24 whose tips face the flange portion. However, the conventional grommet has no sealing mechanism between a bearing face 25a of a tapping screw 25 to be inserted to the cavity of the grommet to fasten it and a head portion 23 of the grommet to be come into contact with the bearing face 25a when the tapping screw is fully fastened, nor between the lower surface of the flange portion 22 and the tips of the stopping claws 24, so that it is in danger of entrance of water into the grommet and/or body through these portions. Therefore, entrance of water has been prevented by applying a grommet whose cylindrical body has a closed bottom 28 to the body 26 and by fitting a sealing annulus 27 such as of sponge rubber between the upper surface of the body 26 and the lower surface of the flange portion 22 when the grommet is applied to the body. However, the above contrivances still involve problems that to fit the sealing annulus 27 imposes an extra operation on an operator, and to form a grommet having a main body with a closed bottom impairs moldability of the grommet, preventing providing of grommets inexpensively.
The present invention is directed to solving the problems inherent in the prior art by contriving the configuration of the grommet and providing an inexpensive synthetic resin grommet which can prevent accurately and securely entrance of water into the grommet and/or body with no extra imposition on an operator.
More specifically, the synthetic resin grommet according to the present invention has a flange portion formed at a predetermined position of a cylindrical body and stopping claws arranged on the outer circumference of the cylindrical body such that their tips face the flange portion, characterized in that the grommet has an annular rib arranged at a top of a head portion of the cylindrical body. Further, the rim portion of the flange portion is preferably formed to have a thin vane-like shape, because sealing between the body and the flange portion can be achieved more accurately and securely. Here, the cylindrical body is preferably designed to have an open bottom, because this improves moldability of the grommet.
Other aspects and advantages of the invention will become apparent from the following description, taken in conjunction with the accompanying drawings illustrated by way of examples the principles of the invention.